Fenix 8 51mm SOLAR Battery Drain

HRM PRO+ and Stryd BUT these drains also occur when I'm at work with no sensors around.

After reading all of these "battery drain posts," I believe that the issue is with the way the F8-watch interacts with the sensors (I'm having a similar issue as you but using  with Coros HR). Try this:

Situation A:

1- Do a soft reset,
2- Do an activity with GPS and without any sensors connected.
3 - After that, you should not experience the battery drain problem.

Situaton B (to reproduce the problem)

1- Do a soft reset,
1. Do an activity with GPS and sensors connected.
2: After that, you should experience the battery drain problem, even when you are not using the watch or close to the sensor, until the next soft reset.

Good evening everyone,
For the benefit of all I would like to share my experience.

F8 Solar 51

For the record, I come from F6X Pro Solar (very happy).

Just received the F8, paired with Smartphone and Update 11.90, 100% charge 30 days.

All the settings are default, I added:
Ringtone for notifications (in addition to vibration);
Phone System Alert (connection disconnection notification which was deactivated by default);
I activated the backlight for touch, notifications and keys in Sleep Focus (it was deactivated);
Activated Security & Detection.

Clarification:
It was the first battery charge!
The backlight (normal mode) by default is always active for notifications, touch and buttons (power a little less than 50%), left as is;
The backlight (Activity mode) No Timeout (always on with power a little less than 75%).

Charge duration 11 days from 02/11 at 23:30 (100% 30 days) to 13/11 at 13:00 (13% 4 days), with 12 hours of eMTB activity (6 activities of about 2 hours, about 3 activities per week), the 12 hours of activity with 4 sensors always connected (Tempe, Cadence, Speed ​​and Heart rate monitor).

I have never done any reboots.

Obviously in these 11 days I have "played" a lot with the F8 to get to know it and become familiar with it by doing many tests, I have made and received some phone calls from the F8, used the LED light (very convenient inside the house in the evening without disturbing anyone) and all the possible notifications of the smartphone (about 200 per day).

I would say that I am very very satisfied, I have not noticed any abnormal discharge (on the day without activity the charge dropped by about 3.5%).

Do you agree with my opinion?
I would like your opinion.

As an update to my prior post to this thread, I’ve done two full battery charge tests now, and not getting nearly the advertised or predicted battery life.  

Settings are: smart watch mode, HR tracking, no activities, no music, backlight only on when I turn it on (or get notifications, etc - I don’t think you can turn that off) with brightness set at less than 25%,  pulse Ox at night only.  The watch is paired with phone, and WiFi is set to “on.”  

When fully charged, the predicted battery life is 26 days (which, I understand, is less than the 30 day advertised smartwatch mode due to pulseox).    Actual battery life is about 16 days.   

For the test, I periodically (once or twice per day) log the time and day and % battery remaining.   In the first test, the battery was totally discharged at 16.25 days.   On the second test, the watch was down to 5% left (predicted 1 day left) after 15.89 days.  Average rate of discharge was remarkably consistent at 0.28% per hour (6.64% per day) in the first test and 0.26% per hour (6.14% per day) in the second test.   So, about 40% less than the predicted battery life at full charge.   

I just gave Garmin access to analyze on their end.  In the meantime, wondering if anyone has made any progress on the issue (with Garmin or on their own).  I only have about three weeks left before the watch needs to go back.  For the next test, I think I'll try without pulseox for the first week, then second week with wifi turned off.  See if these settings make any difference.   

I wrote about this just now on the Enduro 3 forum, but I want to add it here too: this was never mentioned by support, but having the logging enabled on the watch adds a non-insignificant amount of extra battery drain! I ended gathering battery data about 5 days ago and since then I am getting close to the advertised battery numbers (albeit with the most conservative settings possible in smart watch mode, 5% backlight, 4sec timeout, no pulseox, watchface updating once per minute).

For an Enduro 3, this was about 5%/day with logging enabled, and now I can go below 3% without activities. So factor this in as well. I am on 12.19 beta firmware and seems like the baseline drain is not too bad. If you're not trying to solve draining issues with support for weeks, like I was...

Where locate this option: the logging enabled?

This is an extra logging you have to explicitly agree with a Garmin support person, they will push a change to your watch, where you have to also agree to it explicitly on the watch (there's a prompt). It's not enabled by default. I am just mentioning it here because a bunch of people might be also doing this to help out the developers with battery drain issues. And it's good to factor this in.

So it's unlikely you have this enabled if you don't know about it. Still if you want to verify that it's not enabled, you should not have a menu item called "Disable Logging" in Watch Settings -> System. The logging also expires automatically after 2 weeks without disabling it.

This is also not related to 1 second logging vs. smart activity logging. This is general system logging to diagnose issues with the watch.

After much deliberation, I finally decided to purchase the Fenix 8 47mm Solar Sapphire, mainly because of Garmin’s advertised battery life of up to 28 days. Unfortunately, the claimed 28-day battery life is a myth. In smartwatch mode with Wi-Fi off, my Fenix 8 is completely drained after just 3 days. It loses 15% battery overnight alone.

After contacting Garmin's product support team, my Fenix 8 was replaced with a new unit. Sadly, this new device has the exact same issue! The battery is drained again after just three days.

What’s going on here, Garmin?